Fire extinguisher fluid



Patented Aug. 3, 1948 FIRE EXTINGUISHEB FLUID Michael 0. Farris, EagleRock, and John M.

OConnor and Richar Calif., assignors to L tion, Burbank, Calif.

No Drawing. Uriginal an 1941, Serial No. 422,940.

d B. Gottschalk, Burbank,

ockheed Aircraft Corporaplication December 15,

Divided and this application July 1, 1947, Serial No. 758,476

3 Claims. 1

This invention relates to fire extinguishers and more particularly tocompositions for extinguishing fires in finely divided metals such asmagnesium, aluminum, calcium, sodium, potassium, and the like metals andtheir Various alloys.

This application is a division of our prior pending application, SerialNo. 422,940 (now Patent No. 2,432,146), filed December 15, 1941,entitled Fire extinguisher fluid, and relates to nonor semi-dryingvegetable oil compositions for extinguishing burning cuttings ofmagnesium, aluminum, and the like combustible metals and alloys. Ourprior application discloses both fire extinguishing apparatus and fireextinguishing compositions, and claims the vegetable drying oilcompositions disclosed therein.

A number of these metals and their alloys, particularly magnesium andaluminum, are extensively used in the automobile, aircraft and armamentsindustries and in performing the machining operations, for example, inturning, drilling and grinding these metals, large quantities of chips,shavings and finely divided metallic powder is formed which is highlyinflammable and often catches fire and burns violently. Such fires areextremely difilcult to extinguish and heretofore have often resulted inthe loss of the entire body of the metal and also, on occasions, thesimultaneous loss of the valuable machinery and associated equipment bymeans of which these metals are being worked.

Incendiary bombs composed of magnesium, aluminum and sodium aresimilarly difficult to extinguish.

Such fires as those beforementioned cannot be extinguished by the commontype of fire extinguisher fluids such as water, carbon dioxide, andcarbon tetrachloride, for these chemicals dissociate in the presence ofthe incandescent metals and appear to vigorously support combustion tothe extent of actually intensifying the heat and rate of combustion. Inthe case of application of water or steam, for example, the combustionof magnesium becomes practically explosive.

One method which has been attempted in some cases is to cover theburning metal with finely divided solids or powders. For example, suchmaterials as sand, clay, slate powder, calcium carbonate or marble dust,china clay, carbon black, graphite and the like substances have beenused to attempt to cover the burning body of metal with an air-tightblanket which will exelude oxygen. However, these have proved to beunsatisfactory for the reason that the fire continues to Smolderunderneath such a, covering and if resting upon a combustible surfacesuch as a wooden roof or floor will rapidly burn through and, moreover,any subsequent disturbance of the fire covering 50 formed results inimmediate flash of the fire into renewed activity. Furthermore, the useof these solid materials is undesirable when the fire is associated withthe machinery by which the metals are worked, for the reason that theirabrasive properties in some cases would be destructive and in all casesat best damaging. The finely divided metal to which such solid agentsare applied are also rendered substantially unfit for recovery andsubsequent use by reason of the difficulty of separating the pure metalfrom the applied extraneous solids.

Another method which has been attempted to extinguish fires in thesehighly combustible metals has been to apply various oils, waxes andbituminous substances both solid and liquid in ad..1ixture with solidmaterials such as those above mentioned, but these mixtures have provedto be unsatisfactory for the reason, in addition to those beforementioned in connection with the finely divided solids, that they arethemselves in most cases combustible and create a separate fire hazard,particularly when employed in factory buildings and houses, the woodenstructures of which may become permeated with the oil, rendering themhighly flammable. If the applied oil is insufficient to extinguish theburning metal or even at times succeeds in extinguishing the metal, thefire of the burning metal may be replaced by a fire of burning oil orother substances.

It is an object of this invention to overcome the beforementioneddisadvantages of the common type of extinguisher heretofore employed forextinguishing metal fires and to provide a fire extinguisher fluid whichmay be employed freely under substantially all possible conditions toextinguish metal fires whether or not associated with inflammablebuildings or with delicate machinery and which will not create asecondary re hazard.

It has been discovered that fires in metals such as magnesium, aluminum,and the like metals. and their alloys can be readily extinguished bymeans of a properly applied intimate mixture of certain drying,semi-drying and/or non-drying oils and an inert gas such as nitrogen orcarbon dioxide.

Fluids which have been found in accordance with this invention to besuitable are drying, semidrying and non-drying vegetable oils andvarious mixtures thereof. Vegetable oils appear .to be preferable to themineral oils and Of these the drying or semi-drying types have been.found to be more effective in extinguishing the-metal fires,particularly in magnesium.

Suitable drying and semi-dryingloils are linseed, cot-tonseed, soy bean,crotonpbeechnut, corn, pumpkin seed; hemp seed and sesame seed oils, andmixtures thereof. Non-drying oils which have been found to be effectiveparticularly in admixture with certain of the drying types of oils arecastor, palm, peanut, and olive oils.

Cottonseed, linseed and castoroilsand mixtures thereof have been foundto .be'particulariy .effective as employed in this invention, especiallywhen containing admixed nitrogen or preferably carbon dioxide gas in anintimateand finely dispersed form through the oils. Asa specific exampleof the operation of this invention, approximately eight gallons of amixture of two volumes of cottonseed oil having a viscosity of 57seconds Saybolt Universal at 212 -F. and 186 seconds Saybolt Universalat 1 (l0:F. -and a flash point .-of 620 F. to one volume of caster ,oil,havinga viscosity of 1465 seconds Saybolt Universal at -100 F. and aflash point of 505 F. was placed in-the tanlnof the -fire extinguishingapparatus. Carbon dioxide wa admitted to-the-tanl; from-a cylinderthereof to-maintain a gas pressure of approximatelyiOO lbs. per squareinch. The controlling valves were adjusted to produce an oil-gas spraymixture-of creamy consistency. This spray of the'creamy oil-gas mixturewas applied both to the top and base of an intensely burningaccumulation of magnesium shavings and finely divided cuttings. Themixture immediateiypenetra-ted the-quantity of burning metal around its.base and through the top and promptly smothered the flames-and cooledthe remaining metal and its products of combustion. The action of thisextinguishing fluid mixture appears to be acombinationbf blanketing,cooling and a chemical action-Which is not as yet understood. However,the presence of a drying type of-oil in the mixture appears to have afavorable chemical action upon the burning metal in absorbingorexcluding oxygen from the metal surfaces and the combustion zone andthe presence of dispersed carbon dioxide gas in the oil appears to havea cooling effect and "to prevent secondary combustion of the oil uponcon-- tact with the incandescent metal and surround ing inflammablematerial. The castor oil component of the mixture beingof high normalviscosity lends the proper body to the mixture to retain the gas andform a tenacious blanket on the fire.

As another example of the operatiohof this invention approximately eight(8) gallons of peanut oil having a viscosity of 210 seconds SayboltUniversal at 100 F. and a flash pointof 590 F. was placed in the tank ofthe fire extinguishing apparatus. Carbon dioxide was then admitted tothe tank from the cylinder to maintain a gas pressure ofapproximatelyZOO pounds per-square inch. The controlling valves wereadjusted to produce an oil-ga spray mixture of a creamy consistencycontaining the gas in a highly dispersed form. Thespray of this creamyoil gas mixture, issuing from the fan nozzle was applied to the body ofan intensely burning accumulation of magnesium shavings and finelydivided zcuttings. The thus applied extinguishing fluid immediatelypenetrated the body of burning metal cuttings and promptly smothered theflames and cooled the remaining metal and its products .of

non-drying oil appears to ly in this connection by reason of its highfiash combustion. Peanut oil, although classed as a functionadvantageouspoint and apparent relative freedom from formation of smokewhen appliedsto the burning metal.

The formation of the beforementloned creamy mixture of oil containinghighly dispersed gas,

v 3 instead of being accomplished alone by injection of gas directlyinto the stream of oil being ex- ,pelled from'the oil storage tank, alsomay be formed by first introducingthe inert gas into the oilstorage,tanlgand holding it then under pressure for a sufficientitime priortouse to allow a substantial quantity of it t dissolve in the oil. Uponsubsequent release of pressure dissolved gas will be released fromsolutionin a highly dispersed condition and .in sufficient quantity toform the fluid mixture of creamy consistency referred to hereinbefore. f

In cases where deep seated fires occur in large quantities ofaccumulatedmetal-cuttings such as in salvage storage bins it isadvantageous in extinguishing the blaze to thrustthe nozzle into thebody of metal cuttings bymeans of the applicator handle, so as to reachdirectly the point of combustion with the oil spray.

While an oil mixtureratlo of two to one by volume 'of cottonseed oi1--and :castor oil has been foundto be ordinarily preferred, theproportions of the mixture may be varied as desired to produce a fluidmixture of the desired viscosity and consistency to .properly flow fromthe extinguisher unit and'penet-rafte the particular type of metalcuttings to which it is to be applied. Where the unit .is-to-be employedunder extremely low temperature atmospheric conditions, it may bedesirable to substantially reduce the proportion of castor voil tocottonseed oil in order to adjust the fluidity of the mixture to asuitable value.

, The applicationof the oil extinguishing fluid in the-form of aforceful fan-shaped jet by means of the fantype of applicator nozzle hasbeen foundto aid-in the prompt and effective extinguishing of the-finelydivided burning metal.

The foregoing is merely illustrative of the process of the inventionsand is not intended to be limiting. The invention includes any methodand materials which accomplish the objects of the invention within thescope of the claims.

We claim:

1. A fire extinguishing fluid for extinguishing burning cuttings ofmagnesium, aluminum, and the like combustible metals and alloys,comprising as major effective constituents a mixture of an oil chosenfrom the class consisting of castor, palm, peanut and olive oils andmixtures thereof and dispersed carbon dioxide gas in sufficient quantityto form a. fluent foam.

2. A fire extinguishing fluid for extinguishing burning cuttings ofmagnesium, aluminum, and the like combustible metals and alloys,comprising as major effective constituents a mixture of pea-nut oil anddispersed carbon dioxide gas in sufficient quantity to formafiuent foam.

.3. A fire extinguishing fluid for extinguishing burning cuttings ofmagnesium, aluminum, and

